Various shapes of packages containing curable resins have been conventionally used in semiconductors. Such packages contain various metallic materials, which are often integrally molded with the curable resins, for the purposes such as electrically connecting the semiconductors to the outside of the packages, maintaining the strength of the packages, or conducting heat generated from the semiconductors to the outside of the packages.
However, resin generally has a large linear expansion coefficient which is not likely to be matched to the linear expansion coefficient of metallic materials that is generally small. For this reason, some problems, such as warpage, peeling, cracking, and damage to semiconductors, may occur during heat-molding, post-curing, or various processes involving heating and cooling when used as semiconductor components.
Regarding particularly to warpage caused by mismatch of the linear expansion coefficients, a method of molding a curable resin evenly on both sides of a metal has been employed to reduce the warpage.
However, since, in these days, increase in the amount of heat generated from semiconductors has required a design that is excellent in heat dissipation, package designs have been introduced in which a metal to be bonded to a semiconductor element forms a bottom of the package in order to efficiently conduct heat outside the package (Patent Literatures 1 and 2).
In this case, warpage cannot be reduced by the above method, and thus solving the warpage problem is an important issue.
Some improvement of resin in terms of reduction of warpage has been achieved by lowering the linear expansion of resin to be closer to the linear expansion of a metal with which the resin is integrally molded, or by using a resin having a lower elastic modulus.
However, since addition of a large amount of inorganic filler in order to lower the linear expansion reduces the fluidity of resin during molding, and thereby deteriorates the molding processability, such a technique has a limitation. Moreover, a lower elastic modulus corresponds to a reduced strength of resin, leading to loss of the primary function of packages, that is, protection of the semiconductor element.
For the above reasons, curable resins capable of reducing warpage in semiconductor packages have been demanded.
Meanwhile, due to the increase in heat (also light in the case where semiconductors are light-emitting diodes) generated from semiconductors, resins for semiconductor packages have been demanded to have higher thermal resistance (light resistance). In response to such demand, some resins which have high thermal resistance and are cured by hydrosilylation reaction have been employed as resins for semiconductor packages (Patent Literatures 1 and 3).